Routers, bridges and similar network elements implement numerous functions that enable the communication of data from one end of a network to another end of the network. The functions performed by these network elements can encompass functions related to high level control such as configuration of the network element and basic data forwarding. This division of functions is often described as the handling of data in separate planes, a control plane and a data plane.
This division can also be manifest in the architecture of the network elements. The data plane functionality can be largely implemented in a set of components referred to as forwarding elements. Whereas, the control plane functionality can be largely implemented in a set of components referred to as control elements. Network elements with such discrete division of hardware components are often described as having a split-architecture. The control elements and forwarding elements are often implemented as separate line cards. A line card is a discrete component that is removably coupled to the network element. The network element can include any number of these line cards allowing it to scale to handle a large number of network connections. The network element can include multiple control elements and their corresponding line cards to provide distributed control plane implementation or redundant back up in the control plane. Line cards can be replaced to improve the capabilities of the network elements. Line cards are also capable of having their software and hardware upgrade enabling them to take on new capabilities without having the change the line card.